Mitochondrial characterisation of two Spanish populations from the Vera and Bejar valleys (Central Spain).

This survey reports the mitochondrial data of two Spanish populations living in the Vera and Bejar valleys, on the opposite slopes of the Sierra de Gredos (Central Spain), which crosses Spain east to west. The aim of the study was to characterise the mitochondrial genetic pool of the Vera and Bejar populations to investigate a putative mitogenetic differentiation between them, evidence that would support the role of the Sierra de Gredos as a genetic barrier in their micro-evolutionary histories. Blood samples of 137 people (66 from Vera and 71 from Bejar) were collected and mtDNA hypervariable regions I and II (HVR-I and HVR-II) were dissected along with several mtDNA-coding region SNPs. The main European mitochondrial lineages have been found both in Vera and in Bejar, together with the typical African haplogroups L (in Vera) and U6 (in Bejar). FST value and the 95% credible regions calculated for haplogroup frequencies do not reveal genetic differentiation among the populations. Vera and Bejar contain an expected mitochondrial variability within them, but they do not seem to be genetically different from each other, leading us to conclude that the Sierra de Gredos is not a significant genetic barrier in their maternal genetic history.

Mitochondrial DNA Analysis of a Sample of Pre-Columbian Acient Remains from Norte de Santander, Colombia (Chitarera Cultural Area) / Análisis de adn mitocondrial en una muestra de restos óseos precolombinos de norte de santander, colombia (área cultural chitarera)

RESUMEN Los análisis de ADN antiguo (ADNa) han incrementado en los últimos años permitiendo conocer la diversidad genética de las poblaciones precolombinas. En Colombia, existen pocos registros arqueológicos de la población prehispánica del Norte de Santander habitada en el siglo XVI por el grupo Chitarero. Por este motivo, nos propusimos analizar la diversidad genética a partir de secuencias de la región HVRI del ADNmt y determinar sus posibles relaciones con otras comunidades tanto antiguas como contemporáneas. Se analizaron siete individuos precolombinos asociados a este grupo prehispánico, recuperados en los municipios de Cácota y Silos en el departamento de Norte de Santander de los Andes Orientales colombianos, siguiendo criterios estrictos de autenticidad para el ADNa. En todos los individuos se logró identificar el haplogrupo B caracterizado por el polimorfismo en la posición 16217C, siendo éste uno de los más frecuentes en comunidades precolombinas y contemporáneas de los Andes Suramericanos. Este hallazgo indica que este grupo poblacional se encuentra estrechamente emparentado por línea materna, con posibles índices de endogamia, con una probable densidad demográfica baja y una baja diversidad genética, similares a lo observado en comunidades pertenecientes a periodos anteriores como el Formativo. Este grupo precolombino exhibe una de las diversidades genéticas más bajas reportadas en las poblaciones pertenecientes a la familia lingüistica Chibcha. Estos resultados genéticos coinciden con los planteamientos sobre el grupo Chitarero de pertenecer a comunidades pequeñas independientes, con asentamientos dispersos, apartados unos de otros.

ABSTRACT In the last few years there has been an increase in ancient DNA (aDNA) analyses that has allowed shedding light on the diversity of pre-Columbian populations. In Colombia, there are few archaeological records belonging to the prehispanic population from Norte de Santander inhabited in the XVI century by the Chitarero. For this reason, we performed a genetic diversity analysis of the HVRI region of mtDNA in order to determine their possible relationships with other communities both ancient and contemporary. We analyzed seven pre-Columbian individuals belonging to this pre-Hispanic group, recovered from the municipalities of Cácota and Silos in the department of Norte de Santander located at the Colombian Andes, following strict authenticity criteria for aDNA. All individuals were identified as belonging to haplogroup B, characterized by the polymorphism found at position 16217C which is one of the most frequent haplogroups in pre-Columbian and contemporary communities of the South American Andes. This finding suggests that this population group was closely related through its maternal lineage, with possible inbreeding indexes, low population density and therefore low genetic diversity, similar to what is observed in communities belonging to previous periods such as the Formative period. This pre-Columbian group exhibits one of the lowest genetic diversities reported in populations belonging to the Chibcha linguistic family. These genetic results coincide with the views on the Chitarero group as belonging to small independent communities, with dispersed settlements separated among them.

The role of river drainages in shaping the genetic structure of capybara populations.

The capybara, Hydrochoerus hydrochaeris, is an herbivorous rodent widely distributed throughout most of South American wetlands that lives closely associated with aquatic environments. In this work, we studied the genetic structure of the capybara throughout part of its geographic range in Argentina using a DNA fragment of the mitochondrial control region. Haplotypes obtained were compared with those available for populations from Paraguay and Venezuela. We found 22 haplotypes in 303 individuals. Hierarchical AMOVAs were performed to evaluate the role of river drainages in shaping the genetic structure of capybara populations at the regional and basin scales. In addition, two landscape genetic models, isolation by distance and isolation by resistance, were used to test whether genetic distance was associated with Euclidean distance (i.e. isolation by distance) or river corridor distance (i.e. isolation by resistance) at the basin scale. At the regional scale, the results of the AMOVA grouping populations by mayor river basins showed significant differences between them. At the basin scale, we also found significant differences between sub-basins in Paraguay, together with a significant correlation between genetic and river corridor distance. For Argentina and Venezuela, results were not significant. These results suggest that in Paraguay, the current genetic structure of capybaras is associated with the lack of dispersion corridors through permanent rivers. In contrast, limited structuring in Argentina and Venezuela is likely the result of periodic flooding facilitating dispersion.

Out of Africa, but how and when? The case of hamadryas baboons (Papio hamadryas).

Many species of Arabian mammals are considered to be of Afrotropical origin and for most of them the Red Sea has constituted an obstacle for dispersal since the Miocene-Pliocene transition. There are two possible routes, the 'northern' and the 'southern', for terrestrial mammals (including humans) to move between Africa and Arabia. The 'northern route', crossing the Sinai Peninsula, is confirmed for several taxa by an extensive fossil record, especially from northern Egypt and the Levant, whereas the 'southern route', across the Bab-el-Mandab Strait, which links the Red Sea with the Gulf of Aden, is more controversial, although post-Pliocene terrestrial crossings of the Red Sea might have been possible during glacial maxima when sea levels were low. Hamadryas baboons (Papio hamadryas) are the only baboon taxon to disperse out of Africa and still inhabit Arabia. In this study, we investigate the origin of Arabian hamadryas baboons using mitochondrial sequence data from 294 samples collected in Arabia and Northeast Africa. Through the analysis of the geographic distribution of genetic diversity, the timing of population expansions, and divergence time estimates combined with palaeoecological data, we test: (i) if Arabian and African hamadryas baboons are genetically distinct; (ii) if Arabian baboons exhibit population substructure; and (iii) when, and via which route, baboons colonized Arabia. Our results suggest that hamadryas baboons colonized Arabia during the Late Pleistocene (130-12 kya [thousands of years ago]) and also moved back to Africa. We reject the hypothesis that hamadryas baboons were introduced to Arabia by humans, because the initial colonization considerably predates the earliest records of human seafaring in this region. Our results strongly suggest that the 'southern route' from Africa to Arabia could have been used by hamadryas baboons during the same time period as proposed for modern humans.